What is Negative pressure?
The vacuum state created when a high-volume collection machine is connected to a sealed duct system. Air can only flow inward and toward the collector, so dislodged debris exits the system instead of escaping into rooms.
Glossary
Negative pressure
The vacuum state created when a high-volume collection machine is connected to a sealed duct system.
All glossary terms
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Other terms in the glossary
Plenum
The distribution box connected to your air handler — supply plenum on the leaving side, return plenum on the entering side.
Supply duct
The ductwork that carries filtered, conditioned air from the air handler out to the rooms.
Return duct
The ductwork that pulls room air back to the air handler for conditioning.
Source removal
The cleaning method the ACR standard calls for: mechanically dislodge debris inside the duct, then capture it in a vacuum collector outside the living space.
MERV
Minimum Efficiency Reporting Value — the filter-efficiency scale from ASHRAE's test standard.
VOC
Volatile organic compound — vapors off-gassed by paints, adhesives, new materials, and cleaning products.
15+
Years in the field
NADCA ACR
Standard
48h
Written report
< 2hr
Response
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Emergency
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Water intrusion in the ducts, a musty smell that won't quit, or vermin in the system? We answer 7 AM to midnight and every visit ends with camera photos and a written verdict — including a straight "your ducts are fine" when that's what we find. After-hours dispatch runs subject to crew availability.
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